This invention generally relates to medical devices and methods for delivering material(s) to a patient.
Medical conditions sometimes require the replacement or support of a damaged tissue or structure. Such replacement or support can be made via the use of fillers, either temporarily or permanently. Exemplary applications of such filler compositions include sutures and surgical nets that have been used for organ support in spleen, liver, and kidney repair procedures. A non-immunogenic, bioerodible, implantable composition with alginate fibers is known, as is a biological tissue transplant coated with a stabilized multi-layer alginate. Transplantable artificial pancreatic tissue can be prepared from an alginic acid gel precursor, a matrix monomer, and pancreas cells with Ca2+ ions and a matrix monomer polymerization catalyst. The calciumalginic acid composition is used to provide mechanical integrity to the mixture while the matrix monomer is polymerized, after which the calcium-alginic acid composition is removed to leave a porous matrix. The calcium-alginic acid composition functions as a processing aid not as a structural member in the final artificial device. Also, alginate fibers have been used in preparation of wound dressings.
Formation of fibers with ionically crosslinked alginates requires contacting crosslinking agents, such as the cation of choice, with the alginate of choice. While contacting a crosslinking agent with an alginate generally is not considered difficult, controlling the formation and termination of the alginate fibers has been difficult. The difficulty arises from the rapidity in which alginate crosslinks once exposed to crosslinking ions. Controlling fiber formation and fiber termination is a major problem of existing preparation methods that employ the simple mixing of the two agents.
Because of the rapid rate of crosslinking, an alginate and a crosslinking agent generally should be separately delivered to, and crosslinked at, the location in need of alginate fibers. Such in situ formation provides maximum effectiveness in generating alginate fibers with the desired shape and size at the desired location. Introduction and/or relocation of formed alginate fibers generally is not effective or efficient.
One object of the invention involves mixing, delivering, and terminating delivery of a crosslinking agent and a crosslinkable polymer at the location of need, thereby providing efficient delivery of fibrous material and minimizing potential for complications.
In one aspect, the invention relates to a delivery catheter. The delivery catheter can include a first elongated member and a second elongated member. The first elongated member defines a first distal opening, a first lumen extending within the first elongated member, and a distal section of the first lumen near the first distal opening. The first elongated member delivers a first material through the first lumen and into the distal section of the first lumen. The second elongated member includes a distal valve and defines a second lumen extending within the second elongated member. The second elongated member is designed for delivering a second material through the second lumen and the distal valve into the distal section of the first lumen. At least a portion of the second elongated member is slidably disposed within at least a portion of the first lumen such that the distal valve is selectively slidable (i) to allow delivery of the second material through the second lumen, the distal valve, and into the distal section of the first lumen, and (ii) to push at least some of the first and second materials from the distal section of the first lumen out of the first distal opening.
In one embodiment of the invention, the delivery catheter comprises a one-way flowcontrol distal valve such as a slit in the wall of the inner elongated member that opens and closes upon pressure differential. In another embodiment, the delivery catheter further contains an access joint for insertion of at least a portion of the second elongated member into a portion of the first lumen. In yet another embodiment, the delivery catheter further contains a first and second pumps connected to the first and second elongated members. Each of the pumps may further contain an injector. In yet another embodiment, the delivery catheter comprises a stabilizing structure (e.g. spokes) to stabilize the second elongated member so that it is substantially coaxial to the first elongated member. In yet another embodiment, the first elongated member of the catheter is transmutable such that the distal valve is locatable outside the first lumen and outside the first distal opening.
In another aspect, the invention relates to a method for delivering an extrudable material within the body of a mammal. The method includes the following steps. A delivery catheter as described above is provided to deliver a first and second materials into a body. A fibrous material is extruded out of the distal section and into the body of a mammal. In one embodiment, the extrusion step includes delivering through the first lumen to the distal section a first material having a crosslinking agent and delivering through the second lumen to the distal section a second material having a crosslinkable polymer. In one embodiment, the first material surrounds the second material as both materials are introduced into the distal section of the first lumen. The contacting of the first material with the second material results in the formation of crosslinked polymeric material and the generation of a fiber inside the distal section. The sustained delivery of the first and second materials into the distal section forces the fiber to be extruded out of the distal section into a body when the catheter is positioned within a body of a patient. The formation of the crosslinked polymeric material may be stopped by terminating the feed of either or both of the first and second materials into the distal section. The method may further include cutting the crosslinked polymeric material so formed. To cut the polymeric material, introduction of one or both of the first and second materials can be terminated. The crosslinked polymeric material can be cut by the distal valve. To facilitate its exit, the crosslinked polymeric material can be pushed by a pressure exerted from the distal valve and/or by the pressure exerted from the sustained delivery solely of the first material into and out of the distal section.
The foregoing and other aspects, features, embodiments, and advantages of the invention will become apparent from the following description, figures, and claims.